In the last week of July, scientists from around the world converged on Prague. At the 11th Frontiers of Quantum and Mesoscopic Thermodynamics conference (FQMT'26), they explored what quantum mechanics tells us about the world today and how to turn it into the technologies of tomorrow.
Quantum systems and their surroundings
A common idea ran through the first block of lectures. No real quantum system is ever perfectly isolated. Each one constantly exchanges energy with its surroundings, and describing this exchange is the very heart of quantum thermodynamics.
Peter Hänggi named one of the field's problems right at the start: "We have a zoo of approaches to do quantum mechanics in the presence of dissipation." Most of these recipes for describing a system that leaks energy into its surroundings are, in his view, mere shortcuts. Only one procedure is truly reliable: taking into account the full quantum mechanics of the system together with its environment.
Udo Seifert addressed the question of how to measure the extent to which a system is driven out of equilibrium. This is expressed by a quantity called entropy production, which plays a key role in active matter and in the molecular machines inside our cells. An experiment, however, never sees the whole system, only a part of it, and much of what matters remains hidden. Seifert therefore asked what can still be established with certainty even from such an incomplete view.
Ronnie Kosloff built his lecture on a fact that theoretical descriptions often simplify away: "Any quantum system is inherently open, continuously interacting with its environment." Controlling real quantum devices therefore means working with systems from which energy and information continuously leak into the surroundings.
Building and cooling quantum machines
The second block turned to quantum computing. Yuval Gefen introduced the concept of quantum steering, a measurement-based state-engineering protocol that uses repeated observations to shape a quantum system into the desired form. This opens a path to key resources such as quantum entanglement, control over the system, and its cooling.
Joining by video call, Franco Nori presented three recent results on superconducting qubits. These are miniature electrical circuits that behave like artificial atoms and form the basis of many of today's quantum computers. Nori first described a phenomenon in which a single particle of light, a photon, excites two atoms at once, even though a photon ordinarily hands its energy to only one atom at a time.
He then showed how individual photons can be made to act on one another directly. This is remarkable because photons normally pass through each other with virtually no interaction, yet here it was achieved with, on average, barely a single photon in the system. Finally, he presented an experiment in which a 41-qubit chip served as a simulator of other physical systems, testing how an especially robust, so-called topological form of quantum transport copes with the defects and imperfections that no real device can avoid.
Mohammad Ansari closed the morning by pointing to a hidden problem. The properties we value most in quantum devices, such as operational fidelity, quantum entanglement, and entropy, are inherently nonlinear. Put simply, they do not add up or flow through a device as straightforwardly as, say, energy or electric charge. The standard theoretical tools physicists use to track how quantities flow through a device are therefore not up to the task, and new methods need to be developed.
An evening open to the public
After lunch, the conference programme split into three parallel sessions. The first was devoted to many-body systems driven out of equilibrium, with talks by Branislav Nikolić, Michael Galperin, Jordan Horowitz, Gabriele De Chiara, and David Edward Bruschi. The second belonged to quantum information, featuring Alberto Imparato, Henning Kirchberg, and colleagues from Saar Rahav's group. The third focused on quantum optics, with contributions from Dana Anderson, Volker Deckert, Walter Pfeiffer, and Fabio Pistolesi.
On Tuesday evening, the conference opened its doors to the wider public with two popular lectures accompanied by live music. Philippe Grangier first guided the audience along the path "from fundamental principles to technological revolutions," after which Allen Hermann swapped physics for music, showing how jazz musicians improvise and how they communicate with one another and with the audience. The evening culminated in a live jazz concert.
Remembering Anthony J. Leggett
The conference programme ran until Saturday 1 August and featured a number of other distinguished names. On Tuesday, Jian-Wei Pan, a pioneer of satellite quantum communication, gave a lecture on quantum networks linking communication, computation, and metrology. Leo Kouwenhoven presented experiments on Kitaev chains in nanowires.
Thursday evening belonged to the memory of Nobel laureate Anthony J. Leggett, who passed away last year. After a personal remembrance by his long-time colleague Fernando Sols, the public lecture was given by Amir Caldeira, with whom Leggett once created what is now known as the Caldeira–Leggett model, describing quantum systems that lose energy to their surroundings. Caldeira traced how research on macroscopic quantum phenomena culminated in the 2025 Nobel Prize in Physics, awarded for their experimental observation. The evening closed with a concert of classical music.
Friday was largely devoted to biophysics, from molecular motors to an artificial protein capable of walking along a DNA strand. The closing session on Saturday then brought together quantum physics and gravity, featuring, among others, Marlan Scully with a lecture on quantum optics in curved spacetime.